Heating of high chambered horizontal coke ovens



Dec. 7, 1965 .1. BECKER 3,222,260

HEATING OF HIGH CHAMBERED HORIZONTAL COKE OVENS JOSEPH BECKER J mdf@ s AT'roRNEY 7 Sheets-Sheet 2 J. BECKER INVENTOR. ./osL-'PH BECKERblsArroR/ver HEATING OF HIGH CHAMBERED HORIZONTAL COKE OVENS Dec. 7,1965 Filed Jan. 9, 1963 Dec. 7, 1965 J. BECKER 3,222,260

HEATING OF' HIGH CHAMBERED HORIZONTAL COKE OVENS Filed Jan. 9, 1963 '7Sheets-Sheet 5 SECT/0N D-D INVENTOR. Jose/2H BECKER "is ,4 T ToRA/E YDec. 7, 1965 J, BECKER 3,222,260

HEATING OF HIGH CHAMBERED HORIZONTAL COKE OVENS Filed Jan. 9, 1963 '7Sheets-Sheet 4 INVENTOR. JOSEPH BECKER ""'S ATTORNEY Dec. 7, 1965 J.BECKER 3,222,250

HEATING 0F HIGH CHAMBERED HORIZONTAL .COKE OVENS Filed Jan. 9, 1963 7Sheets-Sheet 5 INVENTOR. ./OSEPH BECKER E "'s ATTORNEY Dec. 7, 1965 g,BECKER 3,222,260

HEATING 0F HIGH GHAMBERED HORIZONTAL COKE OVENS Filed Jan. 9, 1963 '7Sheets-Sheet 6 SECT/NEE INVENTOR JOSE PH BECKER ms ATTORNEY Dec. 7, 1965J. BECKER 3,222,250

HEATING OF HIGH CHAMBERED HORIZONTAL COKE OVENS Filed Jan. 9, 1963 '7Sheets-Sheet '7 m5 A r 'rok/v5 Y United States Patent O 3,222,260HEATING F HIGH CHAMBERED HORIZGNTAL CGKE VENS Joseph Becker, Pittsburgh,Pa., assignor to Koppers Company, Inc., a corporation of Delaware FiledJan. 9, 1963, Ser. No. 250,336 6 Claims. (Cl. 202--12) This inventionrelates to improvements in the construction and general operation ofregenerative horizontal coking retort ovens having coking chambers ofsubstantial increase in height over the height of conventional cokingchambers and employing both low burners and high burners in theflame-lines comprising the heating Walls, and more particularly, to thestructuaal arrangement and operation for alternately burning gas in thehigh and low burners during each burning period in the ame-iluessubstantially all of which have one high and one low burner in the sameflue.

.A number of arrangements and proposals have been made with the primaryobject of substantially increasing the production capacity of byproductcoke ovens. However, to date, these attempts have for the most part beenunsuccessful for the coke produced therein is not of that uniformquality required for those metallurgical processes, such as in blastfurnace operation, wherein coke is an important component both becauseof its contribution to the chemical reaction and also because of itsstructural strength for supporting the overburden of ore, limestone andother coke. This metallurgical coke is now produced by coke ovens ofconventional capacity wherein uniformity of heat distribution to thecoals in the coking chamber has, over a period of fty years, beendeveloped to a fine art.

In those instances in which the attempts for greater production havebeen based upon increasing the width of the coking chamber, it has beenfound that the requisite coking time is increased and the output of theoven per unit of time remains low.

In those attempts which have been made to increase oven capacity byincreasing the height of the coking chamber, the greatest deterent hasbeen the inability of the construction proposed to provide a uniformdistribution of heat to the coal in these coking chambers of suchincreased height, because it has been found that the arrangements andrelative disposition of the heating Wall components in those mannersknown in the art of conventional coke oven heating are neither directlyapplicable nor logically extensible to higher-than-conventional cokeovens.

Further, since it is uniformly recognized that higherthan-usual highburners are required to extend the heat of combustion to the upperregions of these taller ues, a very serious problem has arisen inconnection with these latter attempts, that is, clogging of the riserpassages to the high burners. This clogging occurs primarily in theregion from the base of the flue to the high burner por-ts or nozzlesand is caused by the deposition therein of carbon from the thermaldecomposition of rich fuel gas being fed to the high burners. Since itis a distinct advantage to be able to operate coke ovens by burning richgas in the flues, much Veffort has been expended toward seekingsolutions to this serious maintenance problem which not only involvesthe expense and hazard of refurbishing the carbon-clogged risers butalso seriously decreases the overall capacity of the oven by increasing'the down time.

The primary object of the present invention is, therefore, the provisionof improved structural arangements and operating procedures forby-product coke ovens, which improvements Will substantially increasethe capacity of 3,222,260 Patented Dec. 7, 1965 ice the lcoke ovenbattery by providing a solution to the abovementioned problems vexingthe industry.

In brief, to enable high capacity by-product coke ovens having cokingchambers of a height exceeding that of conventional coking chambers byapproximately fifty per cent to produce metallurgical coke, thisinvention consists of an arrangement of elements for the conduct of aprocess for heating a horizontal battery having a highlevel andlow-level gas nozzles in each vertical flue (except perhaps the endilues) whereby the high and low burners will not burn simultaneously butwill burn alternately during each burning period.

By the exercise of this split in burning time between the high-level andthe low-level burners it thereby becomes possible to start high-levellcombustion at that time during which the ue temperature is at itslowest value, just after the heating walls have reversed. Thishigh-level combustion is self-initiating 'and there is no necessity forcombustion at the low-level burners. Thus, by such operation thehigh-level burner riser passages are not exposed to the very high rangeof temperatures which occur in the tlues and the formation of carbon inthe gas riser passages and/or gas burners nozzles, is thereby reduced.As will be described in greater detail below, during the period ofoperation of the low-level burners the supply of fuel gas t0 thehigh-level burner is discontinued and the .riser passages are actuallybeing decarbonized when the flue temperatures reach their maximum value.

In the accompanying drawings forming part of this specilication, thereare shown for purposes of illustration, both a gun flue red battery andan underjet battery, which batteries are of the Koppers Becker design(crossover flue interconnected combustion flue heating system) andcontain those modifications to the control and distribution of fuel gasrequired in the practice of the present invention. In each instance,each ue shown contains both a high and a low burner. However, thisinvention -is not limited in its ,application to the specific types ofovens illustrated in the drawings, but is broadly applicable to theheating system for any cross-regenerative coking retort oven such as mayemploy the single-divided flue system or the double-divided ue system,so long as the means disclosed herein are provided and employed forseparately feeding the high burners and the low burners, one of eachbeing present in each ue, except perhaps in the end ues in each heatingWall.

FIG. l is a diagrammatic vertical section taken transversely of a cokeoven battery employing gun-flue feed of rich fuel gas both to the highburners and to the low burners wherein are embodied the features of thepresent linvention yand wherein the left hand portion of FIG. 1corresponds to a vertical section along line A-A of FIG. 2 and the righthand portion of FIG. 1 corre sponds to a vertical section along line B-Bof FIG. 2;

FIG. 2 is a diagrammatic vertical section longitudinally of the gun-Huebattery illustrated in FIG. 1 and taken along the-line II-II thereof;

FIG. 3 is an elevational view of a portion of the distribution apparatusfor simultaneously controlling the feed of fuel to the on burners andthe feed of decar.- bonizing .air rto t-he off burners;

FIG. 4- is a vertical section taken transversely of an all-underjetbattery employing decarbonizing air in place of waste gas recirculationand embodying the present invention wherein the left hand portion ofFIG. 4 corresponds to a vertical section along line C-C of FIG. 5 andthe right hand portion of FIG. 4 corresponds to a vertical section alongline D--D of FIG. 5;

FIG. 5 is a partial vertical section longitudinally of the underjetbattery illustrated in FIG. 4 and taken along line V-V to show thebution system;

FIGS. 6, 7 and S show the several active positions for the three-waydistributing valve for fuel gas and decarbonizing air;

FIG. 9 is a vertical section taken transversely of an all underjetbattery employing waste gas recirculation and embodying the presentinvention wherein the left hand portion of FIG. 9 corresponds to avertical section along line E-E of FIG. 10 and the right hand portion ofFIG. 9 corresponds to a vertical section along line FF of FIG. 10 andFIG. l is a of FIG. 9.

The coke oven battery illustrated in the accompanying drawings (FIGS. 1and 2) comprises in general a plurality of coking chambers 11 andheating walls 12 that are disposed in alternation progressing in thelengthwise direction along battery 10. Heating walls 12 are made up of aseries of vertical tlame-ues 13, which are individualized heatingchambers, disposed in side-by-side relationship extending crosswise ofbattery 10. These vertical flame-flues 13 are arranged in groups inorder to provide collective flow of the several ame-flues 13 in eachgroup to a common crossover duct 14, whereby the combustion products ofeach flue flows upward, along common horizontal bus ue 16 for each suchgroup of ilues, through duct 14 over the top of coking chamber 11 anddown into the corresponding group of llame-fines 13 on the other side ofthe intermediate coking chamber 11. Thus, each crossover duct 14 can beconsidered as connecting two flow groups of flame-fines 13, one of eachsuch pair of connected flow groups receiving for a period the wastecombustion gases from the burning operation being conducted in the othergroup of the pair. At the end of this period the system is reversed andthereby the relative functions of these flow groups cyclicallyalternate.

Below the coking chambers 11 the oven are arranged a series ofcross-regenerators 17 extending in a direction parallel to the series ofvertical flame-dues 13 in each heating wall 12 and communicatingdirectly therewith. This communication between llameilues 13 andcross-regenerators 17 is achieved through regenerator port and ductassemblies 18.

Although, as is typical for by-product coke ovens, the battery may beheated by the use of regeneratively preheated lean fuel gas, theillustration of this invention is primarily concerned with the operationduring which heating ues 13 are underred with unpreheated rich fuel gas,such as coke oven gas. During such operation, Vall of thecross-regenerators 17 are employed to preheat combustion air to bedelivered to llame-llues 13 through the port and duct assemblies 18. Inthose instances in which it is desired to underfre with lean gassupplementing the lean gas from the regenerators with an enrichingmixture delivered through the distribution system described herein forrich gas underliring, this invention is equally applicable.

The regenerators 17 contain checker-brick and are divided, in the mannerwell-known in the art, into two sets which operate in alternation, oneset receiving the hot combustion products leaving the off set offlameiiues 13 thereby to impart heat to the checker-brick therein andthe other set simultaneously imparting the heat previously stored inchecker-brick to the air passing therethrough during its passage toflame-flues 13. The air so heated reaches a temperature of at least 2000F.

When the battery 10 is heated by rich fuel gas, which has highercaloriic value and therefore needs no preheating step for effectingcoking temperatures quickly and reliably, this rich gas is delivered tothe ame-flues 13 through a series of gas-gun ues 19, 21 runningcrosswise of battery 10 in the corbel region below the floor of heatingwall 12.

fuel gas; air valving and distripartial vertical section taken on lineX-X in the lower story of As shown, the gun liues are arranged in pairswith each gun flue 19 supplying fuel gas to all of the high burners 22(one per flame-flue 13) in half an entire heating wall 12 and with eachgun flue 21 supplying fuel gas to all of the low burners 23 (one in eachllame-flue 13) along half an entire heating wall 12. However, as will bemore completely Ideveloped below, whenever either one of each pair ofgun flues 19, 21 is engaged in the delivery of fuel gas, the other gunflue of the pair is employed for delivering decarbonizing air. Thesupply of fuel gas to all of the pairs of gun ilues 19, 21 on the twosides of the battery 10 is provided by gas mains 24, 26 runninglongitudinally along either side of battery 10.

Thus, main 24 supplies fuel gas for every gun flue 19 and 21 along theentire pusher-side half of battery 10 while main 26 supplies fuel gas toevery gun flue 19, 21 servicing the coke-side half of battery 10.Similarly disposed along the pusherand coke-sides of the battery are airconduits 27, 28.

The manner of distribution of both the fuel gas from main 24 and of theair from air conduit 27 (at which point the air is under pressure) tothe pairs of gun ilues 19, 21 is most clearly illustrated in FIG. 3.Thus, depending upon the particular setting of valves 29, fuel gas maypass through pipe 31 and either pipe 32 or pipe 33 leading to gun tlues19 and 21 respectively and, simultaneously, decarbonizing air will passvia conduit 34 and either pipe 33 and 32 leading to gun flues 21 and 19respectively so as to alternate with the fuel gas feed.

In the arrangement in FIG. 3 disposition of the valve 29 to the farright of the three valve connections illustrated is shown servicing anoff heating Wall and fuel gas cannot pass through the valve.Decarbonizing air is, however, free to pass both to gun flue 19 and to`gun flue 21. The disposition of the two valves 29 to the left of FIG. 3are shown servicing two on heating walls which are separated, of course,by coking chamber 11. Through each of the latter valves 29, fuel gas isbeing supplied to the low burners of the on walls and decarbonizing airis being supplied to the high burners only of these same on walls; thusfuel gas will flow via pipes 31 and 33 to gun flue 21 and decarbonizingair will flow via pipes 34 and 32 to gun flue 19.

Reversing cables 37 and 38 are each connected by a plurality of leverarms 39 to the various valves 29 with alternate pairs of valves 29 beingconnected to one reversing cable and with the intermediate pairs ofvalves 29 connected to the other cable.

This valving and distribution arrangement as illustrated and describedis for the express purpose of providing in a gun-flue battery having ahigh level and a low level gasv nozzle in each flame Hue means by whichthese two nozzles within each ilue will not burn simultaneously but willburn alternately during each burning or on period. For example, ifbattery 10 is being operated on thirty minute reverses, in any givenflame-Hue 13 a first nozzle will burn for some definite time interval ofperhaps eighteen minutes while air received under pressure at the airconduit 27 is conducted to the second burner nozzle in this flue. At theend of this period, the fuel feed to the first burner nozzle will be cutolf, fuel feed to the second nozzle will begin and the air will besupplied to the iirst nozzle. Then, during the remaining portion of thethirty minute cycle, that is for twelve minutes, the second nozzle willburn and the first nozzle will be decarbonized. The split intervals ofburning time between the two burner nozzles can be set by the operatorat his discretion to enable him to produce uniform temperatures over theside wall faces of the charge in the coking chamber 11.

Thus, as an illustration of oven battery operation with the presentinvention, considering half of heating wall 12 immediately after havingbeen reversed to the on cycle, the appropriate reversing cable 37 or 38will have been actuated to position valve 29 as shown in FIG. 6. Withthis positioning of the rotatable element of valve 29, pipe 31 leadingfrom fuel gas main 24 (or 26) is placed in Comunication with pipe 32leading to gas gun 19 and pipe 34 is placed in communication with pipe33 leading to gas gun 21.

Thereafter, for some desired time interval, fuel gas will pass from thegas main, through pipe 31, valve 29, pipe 32, gas gun 19 and riserchannels 41 to high burners 22. At the same time heated air will besupplied to the length of heating Wall 12 throughout the entire onperiod from regenerators 17 via port and duct assemblies 18 at a rate offlow determined by the position of air-port plugs 42. The incoming airfrom regenerators 17 has a temperature of about 2,000 F. and combustionis immediately initiated at the high burner and burning proceeds throughthe burning time interval. An important feature of this sequence ofoperation is the fact that exposure to high temperatures of the fuel gaspassing through risers 41 is restricted to the lowest range oftemperature which occurs in flame-flue 13 during the on period. Therebythe tendency of carbon to form in gas risers 41 as well as in the highburner nozzles 43 is reduced. At the culmination of the high burnerburning interval the proper reversing cable 37 or 33 is actuated andlever arm 39 is moved counter-clockwise 90 to assume the positionillustrated in FIG. 8 whereby for the balance of the reverse fuel gaspasses from main 24 to low burners 23 via pipe 31, valve 29, pipe 33 andgun flue 21. Simultaneously with the redirection of the gas liow asdescribed is the redirection of the decarbonizing air which enters valve29 through pipe 34. This air will now be admitted to the high burners 22through pipe 34, gun llue 19 and riser 41 throughout the burning periodfor low burners 23.

Thus, the burning cycle in any given vertical flame-flue 13 is splitbetween the high burner and the low burner and while either one of thesetwo burners is receiving fuel gas the other burner will be subject todecarbonizing action by pressurized air. Depending upon the type ofbattery, the pressure of the decarbonizing air at a point immediatelypreceding admission to valve 29 is in the range from 1/2 to 10" ofwater.

Upon completion of the reverse, lever arm 39 is rotated through a 45sweep to assume the position shown in FIG. 7. In this position valve 29prevents fuel gas from being fed to either of the gun flues connected tothe off heating wall, while air is supplied to all burners in the offheating wall throughout the off period. At the same time in anotherheating wall located to one side `of the heating wall for which the oncycle has. been described above, the appropriate reversing cable 37, 38adjusts the valve 29 controlling the distribution of fuel gas and air tothis other wall whereby the latter heating wall begins its on portion ofthe reverse.

The same general process of operation described above in connection withan all gun flue battery is equally applicable to an all underjet batteryas is illustrated in FIGS. 4 and 5. Battery 50 shown therein containsessentially the same elements of construction as have been describedabove in connection with the gun flue battery except that the gun ues 19and 21 have been supplanted by the underjet nozzle and riser feeddevices 59 (to high burner) and 61 (to low burner). Only the single gasmain 64 shown extending along the pusher side of the battery isrequired. The gas distribution system from gas main 64 to the burners invertical ame fiues 53, one high burner 62 and one low burner 63 in eachflue 53, consists, in the case of the high burners 62, of pipes 71, 72,header 59a and riser 59. As shown, riser 59 extends upwardly through theregenerator wall and through the bottle brick in the tie wall separatingadjoining flame ues 53 to high burner 62. In the case of low burners 63,distribution is effected via pipes 71, 73, header 61a `and riser 61exflue 53 is split allotting separate and distinct time intervals forburning at the high burner 62 and for burning at the low burner 63,remains substantially the same as has been described in connection withthe gun flue battery.

Decarbonizing air is supplied through conduit 67 and pipe 74 and fuelgas is supplied from the main 64 and pipes 71. As in the description forbattery 10, this battery S0 although operable either by underring withregeneratively preheated lean fuel gas or with unheated rich fuel gaswill be described in connection with the latter mode of fuel feed sincethis is the more likely application of this invention. As statedearlier, however, it is to be understood that this invention is alsoapplicable [for feeding an enriching kmixture to the flues 4during leangas underring.

In any given flame flue 53 during the on cycle, preheated air isadmitted to the llame flue 53 from regenerators 57 through port and ductassemblies S8. Rich fuel gas is admitted through either the high burner62 or the low burner 63 in the above described split sequence ofoperation through gas risers 59 and 61 respectively. Valves 69 arecontrolled by means -of lever arms 79 connected to one or the other ofcontinuous reversing cables 77 and 78, rst, to connect the fuel gas main64 to Asupply fuel gas to high burner 62 and simultaneously therewith tosupply decarbonizing air to low burner 63; then to switch the supply offuel gas from high burner 62 to low burner 63 and simultaneouslytherewith to provide decarbonizing air to high burner 62; and finally,at the end of the re- Verse, to shut off completely the supply of fuelgas to this given llame flue 53 but to continue the application ofdecarbonizing air to both high burner 62 and low burner 63 throughoutthe off portion of the reverse.

During the off portion `of the reverse the waste gas products ofcombustion from the corresponding flow group of on llame flues in theheating wall 52 on the opposite side of adjacent coking chamber 51 willenter these off ilues via crossover duct 54 and then will pass directlydownward through the port and duct assemblies 58 to the regenerators 57in the manner well known in the art.

In FIG. 5 the position of riser 61 relative to riser 59 variesproceeding from left to right in order to retain the position of riserS9 in the center of flue 52 with the arrangement of regenerator wallsshown. With such an alternation of the positioning of these risers asimple arrangement of reversing cables which may be employed comprisestwo continuous cables 77 and 78. Alternate pairs of valves 69 will beconnected to the same reversing cable and in any given pair of valves69, one will be connected to the forward run (77 f or 787) of a givenreversing cable and the [other will be connected to the rearward run(77r or 78r) of lthe given reversing cable thereby to compensate for theabove-mentioned alternation.

Although the two constructions shown in FIGS. 1 through 5 represent inthe first instance an all-gun flue battery, and in the second instancean all-under jet battery, this invention is equally applicable to ac-onstruction combining the gun flue and the underjet designs, which maybe referred -to as a half gun-flue, half underjet design. In such aconstruction a gun flue would be employed to feed fuel gas to the highnozzles in the fashion illustrated in FIGS. l and 2 and underjet ductswould be employed to feed fuel gas to the low burners in the fashionshown in FIGS. 4 and 5. A valving and distributing mechanism similar tothose disclosed in FIGS. 3 and 5 may be employed to provide for thealternate burning of the high and low burners in each flue and also, ifdesired, for the distribution of decarbonizing air to these burnersduring their off periods.

In those all-underjet batteries wherein provision is made for waste gasrecirculation in the fashion well known in the art, air decarbonizationneed not be employed. Such construction is disclosed in FIGS. 9 and l0in combination with means for practicing this invention.

In battery 90 a high burner 91 4and a low burner 92 is provided in eachflame flue 93 with both high burners 91 and low burners 92 beingsupplied with fuel gas by way of underjet risers 94 and 96 respectively.Pairs of underjet risers 96 leading to adjacent ues 93 areinterconnected by means of common chambers 97 in the region below thesole flues and the common chambers 97 to either side of any given cokingchamber 98 are interconnected in pairs by means of waste gasrecirculating ducts 99 in the conventional manner. In similar fashionwaste gas recirculation for the high burners 91 is provided with commonchambers 101 connecting pairs of risers 94 servicing adjacent flues 93and with these common chambers 101 interconnected in pairs, one toeither side of the coking chamber 98, by means of waste gasrecirculating ducts 102.

Headers 94a and 96a respectively supply fuel gas to underjet risers 94and 96 respectively, these headers 94a and 96a being connected via pipes103 and 104 respectively to common supply pipe 106 leading from rich gasmain 107. Valve 108 connected via lever arm 109 to continuous reversingcables 111 (111f and 111r) and 112 (112)t and 112r) provides for theoperation of battery 90 as has been described in connection with splitoperation of the high and low burners in the underjet batteryillustrated in FIGS. 4 and 5.

For the sake of standardization valve 108 may be the same threeway valveas valve 69 employed in the preceding constructions, the valve beingmodified by closing otf the air inlet pipe by means of a shut olf valveor by the use of a permanent cap.

It should be understood, of course, that the foregoing disclosurerelates specically to only one operating cycle in order to illustratethe present invention but that the battery operators may in each giveninstance determine the optimum time intervals of split operation betweenthe high and low burners for the particular battery design withoutdeparting from the spirit and scope of the invention as set forth in theappended claims.

What is claimed is:

1. In a horizontal coke oven battery including elements to provideuniform heating for high-chambered ovens, the combination comprising:

(a) paired groups of flame flues operable alternately in an on and offcombustion condition;

(b) a high burner and low burner in each of said flues;

(c) a source of fuel gas connected to a fuel gas distributing system;

(d) a supply of air under pressure connected to an air distributingsystem;

(e) conduit means communicating said high burners;

(f) conduit means communicating said low burners;

and

(g) valve means connecting said high and low burner conduit means andsaid air and fuel gas distributing systems, operable to pass said airsimultaneously and continually to said high and low burners when saidame flues are in the off combustion condition.

2. In a horizontal coke oven battery including elements to provideuniform heating for high-chambered ovens, the combination comprising:

(a) paired groups of flame flues operable alternately in -an on and olfcombustion condition;

(b) a high burner and a low burner in each of said flues;

(c) a source of fuel gas connected to a fuel gas distributing system; n

(d) a supply of air under pressure connected to an air distributingsystem;

(e) conduit means communicating said high burners;

(f) conduit means communicating said low burners;

`and

(g) valve means connecting said high and low burner conduit means andsaid air and fuel gas distributing systems, operable to simultaneouslypass said air to said low burners and said fuel gas to said high burn- 8ers during a portion of the on combustion condition of said ame ues andoperable to pass simultaneously and continually air to said high burnersand said low burners during the off combustion condition of said flameilues.

3. The invention set forth in claim 2 wherein:

(a) during another portion of said on combustion condition said valvemeans simultaneously passes said air to said high burners and said fuelgas to said low burners.

4. A method of underring a regenerative coke oven battery by means of ahigh and a low burner located in each vertical llame flue in the heatingwalls alongside the horizontal coking chambers, the low burners being atthe base of the ues and the high burners being at a level above thelower burners, and cross-regenerators therefor being located underneaththe coking chambers and heating walls, said method comprising:

(a) supplying fuel gas to the high burners in a given group of on flameflues during a portion of a given on period, and simultaneously (b)supplying regeneratively heated combustion air to said given on flametlues for the entire given on period, and simultaneously (c) supplyingdecarbonizing air to the low burners in said given group of on llamefiues during said portion of said given on period;

(d) selectively controlling the rate of flow of the regenerativelyheated air to said given on flame flues;

(e) discontinuing supplying the fuel gas to said high burners andthedecarbonizing air to said low burners, and thereafter (f) simultaneouslysupplying said fuel gas to said low burners and said decarbonizing airto said high burners during the remaining portion of said given onperiod;

(g) discontinuing supplying fuel gas and decarbonizing air to the highand low burners of said given group of flame flues during the o heatingcondition thereof; and

(h) simultaneously with such discontinuance, supplying decarbonizing airto both said high burners and said low burners during said off heatingcondition in said given group of llame ilues.

5. A method of underring a regenerative coke oven battery by means of ahigh and low burner located in each Vertical llame ue in the heatingwalls alongside the horizontal coking chambers, the l-ow burners beingat the base of the ues and the high burners being at a level above thelower burners, and cross-regenerators therefor being located underneaththe coking chambers and heating walls, said method comprising:

(a) supplying fuel gas to the high burners in a given group of on flameues during a portion of a given on period, and simultaneously (b)supplying decarbonizing air to the low burners in said given group of onflame flues during said portion of said given on period;

(c) discontinuing supplying the fuel gas to said high burners and thedecarbonizing air to said low burners, and thereafter (d) simultaneouslysupplying said fuel gas to said low burners and said decarbonizing airto said high burners during the remaining portion of said given onperiod;

(e) discontinuing supplying fuel gas and decarbonizing air to the highand low burners of said given group of flame ues during the off heatingcondition thereof; and

(f) simultaneously with such discontinuance, supplying decarbonizing airto both said high burners and said low burners during said off heatingcondition in said given group of flame tlues.

6. In the method of underring a regenerative coke oven battery by meansof a high burner and a low burner located in each vertical flame ue inthe heating Walls alongside the horizontal coking chambers, the lowburners being at the base of the flues and the high burners being at alevel above the low burners, the steps comprislng:

(a) supplying alternately fuel gas and decarbonizing air to said highburners during a given on heating period, and therewith simultaneously(b) supplying alternately decarbonizing air and fuel gas to said lowburners during said on heating period; and thereafter (c) supplyingsimultaneously and continually decarhonizing air to `both `said highburners and said low burners during the off heating condition of saidheating ilues.

References Cited by the Examiner UNITED STATES PATENTS MORRIS O. WOLK,Primary Examiner.

1. IN A HORIZONTAL COKE OVEN BATTERY INCLUDING ELEMENT TO PROVIDEUNIFORM HEATING FOR HIGH-CHAMBERED OVEN THE COMBINATION COMPRISING: (A)PAIRED GROUPS OF FLAME FLUES OPERABLE ALTERNATELY IN AN "ON" AND "OFF"COMBUSTION CONDITION; (B) A HIGH BURNER AND LOW BURNER IN EACH OF SAIDFLUE (C) A SOURCE OF DUEL GAS CONNECTED TO A FUEL GAS DISTRIBUTINGSYSTEM; (D) A SUPPLY OF AIR UNDER PRESSURE CONNECTED TO AN ADISTRIBUTING SYSTEM; (E) CONDUIT MEANS COMMUNICATING SAID HIGH BURNER(F) CONDUIT MEANS COMMUNICATING SAID LOW BURNER AND (G) VALVE MEANSCONNECTING SAID HIGH AND LOW BURNER CONDUIT MEANS AND SAID AIR AND FUELGAS DISTRIBUTION SYSTEMS, OPERABLE TO PASS SAID AIR SIMULTANEOUSLY ANDCONTINUALLY TO SAID HIGH AND LOW BURNERS WHEN SAID FLAME FLUES ARE INTHE "OFF" COMBUSTION CONDITION.
 6. IN THE METHOD OF UNDERFIRING AREGENERATIVE CO OVEN BATTERY BY MEANS OF A HIGH BURNER AND A LOW BURNERLOCATED IN EACH VERTICAL FLAME FLUE IN THE HEATING WAS ALONGSIDE THEHORIZONTAL COKING CHAMBERS, THE LOW BURNERS BEING AT THE BASE OF THEFLUES AND THE HIGH BURNERS BEING AT A LEVEL ABOVE THE LOW BURNERS, THESTEPS COMPRISING: (A) SUPPLYING ALTERNATELY FUEL GAS AND DECARBONIZING ATO SAID HIGH BURNERS DURING A GIVEN "ON" HEATING PERIOD, AND THEREWITHSIMULTANEOUSLY (B) SUPPLYING ALTERNATELY DECARBONIZING AIR AND FUEL GASTO SAID LOW BURNERS DURING SAID "ON" HEATING PERIOD; AND THEREAFTER (C)SUPPLYING SIMULTANEOUSLY AND CONTINUALLY DECARBONIZING AIR TO BOTH SAIDHIGH BURNERS AND SAID LOW BURNERS DURING THE "OFF" HEATING CONDITION OFSAID HEATING FLUES.